mm: khugepaged: recalculate min_free_kbytes after stopping khugepaged

mm: khugepaged: recalculate min_free_kbytes after stopping khugepaged

When initializing transparent huge pages, min_free_kbytes would be
calculated according to what khugepaged expected.

So when transparent huge pages get disabled, min_free_kbytes should be
recalculated instead of the higher value set by khugepaged.

Link: https://lkml.kernel.org/r/1633937809-16558-1-git-send-email-liangcaifan19@gmail.com
Signed-off-by: Liangcai Fan <liangcaifan19@gmail.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>